I put on a new start/Gen on my 154. I replaced the old one for the same reason.(Old s/g bench tested fine...who knew)

The starter will make one or two revs then hits a tight spot. It zaps the battery quickly. Does it while being jumped from my truck too. It just can't get the revs up to start. I know these are slow starters but this is almost acting like it's on a dead battery. Even being jumped.

The whole electrical system is new.(2 years)New selenoidElectronic ign.New clutch and clutch brake (well adjusted)All voltage where it's supposed to be.Adjusted belt from tight until slippingS/G spins fine without belt.Battery is always at 12v+.

Since electric is fine and no binding with trans (disconnected axle) I took out the plugs. Spins like crazy. All valves appear to be moving. (lots of carbon) Oiled the cylinders anyway. I put it back together and it's doing the same thing. Almost acts like a vapor lock. (carb torn down and cleaned twice) But sometimes will spin and fire right up. When it runs, it runs strong. I figured if it was a mechanical issue, the motor would run rough or vibrate. Sludge? Bent piston rod? Gremlin? Family of gremlins?

Any crazy ideas are welcome. I know this tractor back to front at this point and can not get my head around this.

I have bypassed the clutch switch and even disconnected the drive axle to eliminate that as a possibility. All cables new, battery terminals clean. Cables are larger than oem. No restriction.The ground/negative battery cable is on the transmission case. Took a wire wheel and it's bare metal to bare metal.New selenoid is against bare metal as well.

The only two things that get hot are the positive cable off the battery and the s/g itself.

It's as if the engine is binding in some way. Again, it seems mechanical but maybe I'm losing enough amperage/voltage to something else I'm missing entirely. And it's enough to zap the power when there's compression.

Then again, as if it's a vapor lock situation, it will all of a sudden clear up and spin.

Simple way to check the high current part of the electrical system. Connect a voltmeter between the terminal on the S/G and the battery positive terminal. Not the battery clamp. Turn the starter on and read the meter. Anything over a half volt indicates a problem in the connections between battery terminal and starter terminal. Under half a volt and there is no problem with the positive connection. Do the same test with the voltmeter connected between the S/G frame and the battery negative terminal. Again, not the cable clamp but the actual battery terminal. Anything over .4 volts is a problem. If the voltage readings are good you have no problem with the electrical system as long as you have a good battery.

Larry B wrote:Simple way to check the high current part of the electrical system. Connect a voltmeter between the terminal on the S/G and the battery positive terminal. Not the battery clamp. Turn the starter on and read the meter. Anything over a half volt indicates a problem in the connections between battery terminal and starter terminal. Under half a volt and there is no problem with the positive connection. Do the same test with the voltmeter connected between the S/G frame and the battery negative terminal. Again, not the cable clamp but the actual battery terminal. Anything over .4 volts is a problem. If the voltage readings are good you have no problem with the electrical system as long as you have a good battery.

Thank you. I'll do that test today. Even thugh it seems mechanical in nature, something in my brain is telling me I'm missing something in the electrical. I'm guessing there's enough of a voltage drop in the system that it appears to struggle against the engine.

When I rebuilt the electrical system, the factory 8 pin connector was shot. (tractor was in a building that caught fire years ago, melted most of the plastic) I rewired the whole thing using a marine bus bar system (I'm a boat guy) and heavy gauge thhn wires with heat shrink terminals. Pretty much all 12ga wire too. So there shouldn't be any restriction on electrons. I'll go through and test each circuit individually.

Larry B wrote:Simple way to check the high current part of the electrical system. Connect a voltmeter between the terminal on the S/G and the battery positive terminal. Not the battery clamp. Turn the starter on and read the meter. Anything over a half volt indicates a problem in the connections between battery terminal and starter terminal. Under half a volt and there is no problem with the positive connection. Do the same test with the voltmeter connected between the S/G frame and the battery negative terminal. Again, not the cable clamp but the actual battery terminal. Anything over .4 volts is a problem. If the voltage readings are good you have no problem with the electrical system as long as you have a good battery.

I tested it today.

Positive terminal to s/g .39 volts.Negative to case, .26 volts.

By passed everything. Disconnected regulator and batt cables from s/g. Jumped directly from running truck. Same thing. Spins slowly about one rev then lopes.

I ended up taking out the plugs again. Took off side plate to check the valves. I spun the engine and all went fine. All valves moving and well lubricated. Checked oil filter housing and oil pumps strong.

What I did find in the side of the motor is some very fine flakes of metal. About the size of a fingernail. As I poked around I found that they came from the top of the valve area, close to where the valves penetrate up to the combustion chamber. They were flaking from the block. Still, they were more delicate than a potato chip and alone wouldn't have the integrity to jamb up the valves or cam. But I thought if it was happening for a while it may have caused issues..

I decided to dump the oil. I flushed out the pan and then ran a telescoping magnetic probe into the oil drain. It came out with what I'd expect, a little bit of metal "dust" or grit. I checked the oil filter and it's fine. Nothing in the filter and nothing major in the filter housing. Just some mild sludge.